The cut rating of a polished diamond reflects the capability of the master craftsman to reveal the fire and sparkle of the rough uncut gemstone. A diamond's brilliance is maximized through the proper proportions of depth and width, polish and symmetry of its facets. A diamond with high color and clarity will look dull if not cut properly. For this reason, most gemologists agree that the quality of the diamond cut is the most important of the 4C's.

Diamond Structure
Before we begin, it is important to understand the structure of a polished diamond.

Diameter: The width of the diamond measured from the girdle
Table: The largest horizontal facet of the diamond
Crown: The upper part of the diamond above the girdle
Girdle: The narrow area around the circumference of the diamond
Pavilion: The bottom part of the diamond below the girdle
Culet: The bottom tip of the diamond which may be a point or a facet.



A well cut diamond allows light to enter the table facet, travel through the pavilion where it will be reflected from one side to another, then reflect back out through the table facet.

A poorly cut diamond will allow the light to "leak" out from the sides or bottom of the pavilion rather than reflect back out the top facet. Less light reflection equals less brilliance

Polish and Symmetry
Polish and Symmetry are two important factors that determine the make or workmanship of a diamond. The symmetry grade on a diamond report refers to the alignment of diamond facets. Each round diamond has 58 facets that must be proportionately sized and aligned. Without proper symmetry, the light entering a diamond is misdirected as it enters and exits the diamond resulting in poor dispersion. The polish grade describes the smoothness and uniformity of smoothness of the diamond facets. A poorly polished diamond will have polish lines and a rougher texture that creates a duller surface.

The polish and symmetry grades are clearly listed in each diamond grading report. For AGS Laboratories, the grades range from Ideal (ID), Excellent (EX), Very Good (VG), Good (G), Fair (F) and Poor (P). For GIA Laboratories, the grades range from EX to Poor.



Cut Grade
The finest cut diamonds are those whose proportions follow a formula of ideal facet alignment, crown angles, and ratio of depth to diameter. This attention to detail by the diamond cutter toward producing the most ideal proportions and symmetry of the finished product results in the maximum brilliance of the diamond.

Before a diamond cutter begins the process of creating a polished diamond from a rough gem crystal, he must determine whether or not to sacrifice carat weight to create a smaller, finer cut diamond, or try to create the largest diamond possible from the rough, thereby sacrificing quality of the cut.

Although the Gemological Institute of America (GIA) grades the proportion and symmetry of a diamond, it will not determine an overall cut grade. The American Gemological Society Laboratories (AGS) are responsible for an overall cut grade, and have developed a table that details the specific criteria to grade the cut of a particular diamond. These cut grades range from 0-10 and are categorized as AGS Ideal (0), AGS Excellent (1), AGS Very Good (2), AGS Good (3-4), AGS Fair (5-7) and AGS Poor (8-10).

Cut Scale:
0 = rarest and most desirable
10 = least desirable



- Ideal cut Diamonds are cut to maximize the brilliance of the polished gem. The precision and craftsmanship is characterized by smaller table sizes and a distinctly superior dispersion that is easily recognizable when compared against a non-ideal cut diamond. The diamond cutter usually sacrifices much of the rough gem crystal to produce a smaller, finer cut stone with ideal proportions. These diamonds are cut according to specific AGS Ideal Cut criteria and are the finest diamonds on the market.

- Excellent cut diamonds have been afforded the same attention to detail as the AGS Ideal Cut diamonds, however have a very slight departure from ideal and are thus priced slightly lower than the AGS Ideal Cut diamonds. These Excellent Cut grades allow the consumer the choice to purchase an excellent quality cut at a more affordable price.

- Very Good cut diamonds reflect most of the light that enters them and have a great deal of brilliance and scintillation. The diamond cutter has preferred to take creative license and create a larger diamond by straying a bit from the rigid standards of the AGS Ideal Cut. Although most of the parameters meet the AGS standards, these diamonds will not meet the AGS Ideal certification requirements.

- Good cut diamonds have been cut to create the largest possible carat weight from the rough diamond crystal. Thus rather than cut a smaller, premium diamond the cutter has decided to keep the weight and offer as much brilliance as possible. These diamonds are an excellent value for customers who want to meet their budget and not sacrifice quality or beauty.

- Poor/Fair cut diamonds are not considered to be a good value for the price. A consumer who purchases an otherwise good quality diamond with a Poor/Fair cut grading may feel he or she is getting a "good deal" however the diamond will have poor light reflection and is not considered a wise investment.

What Cut to Buy

• For superior brilliance and value, select a diamond with a cut grade of Very Good or Good, and Polish/Symmetry grades of Very Good or Good.
  
• Buy focusing on a higher Cut or Polish/Symmetry grade, you can meet your budget requirements by selecting diamonds in the near-colorless/SI quality range. These diamonds provide great overall value for your budget.